Oscillatory mill with air separation



5m, 22, 1957 UNKE OSCILLATOR! MILL WITH AIR SEPARATION Filed May 23, 1955 JNVENTOR. GERHARD LINKE ATTORNEYS United States Patent OSCILLATORY MILL WITH AIR SEPARATION Gerhard Linke, Mulheim-Ruhr, Germany, assignor to N. V. Tema, The Hague, Netherlands, incorporation of the Netherlands Application May 23, 1955, Serial No. 510,307 Claims priority, application Germany July 19,1951

2 Claims. (Cl. 241-47) It is known to use rotating tube mills or ball mills with air separation. The object of these mills is to remove the material which has been suificiently comminuted from the grinding zone and to return the material which is taken along but which has not yet been sufficiently comminuted, the so-called grit, to the mill. Seeing that the ball mills rotate the separator connections are to be provided with stufiing boxes or the like. Moreover special measures are to be taken to prevent the air circulation from becoming too large and the moving parts from becoming too oily and to avoid wear and tear of said parts.

Instead of all kinds of rotating ball mills so-called oscillatory mills have come into use, the grinding containers of which are likewise filled with balls or with cylindrical elements such as shaft or pipe sections. Oscillatory mills do not rotate, however, but they are given a substantially circular rapid oscillation. If the material which has been sufliciently comminuted is at an early stage removed from the circulating material to be ground and the comminuting bodies, the efficiency both as regards the quantity and the quality will increase considerably. The vibrating mills oifer a great many structural and technical advantages for the provision of an air separator. Since they do not rotate it is not necessary to connect the inlets and the outlets via stufiing boxes or labyrinths. Resilient impermeable metal tubes, rubber pipes or the like are rather used for the connections. As moreover the circumference of the total quantity of grinding bodies always remains the same in respect of the walls of the vessel this filling of grinding bodies itself can in addition be used as an impact separator and thus a particularly fine separation is obtained which is even promoted by the fact that all the grinding bodies are in a continuous slightly vibrating motion relatively to one another and the material to be ground is accordingly loosened and made accessible to the separating airstream with a particular effect.

In known oscillatory mills with air separation the material to be ground, i. e. the material in coarse condition and the separating air are supplied to the grinding container separately, to which end the grinding container in an upper wall is provided with two adjacent supply openings. In a mill of this type it is not possible to pass the separating air uniformly through the grinding bed, e. g. grinding balls. However, in order to obtain a satisfactory and rapid separation it is highly desirable to have the separating .air distributed most uniformly over the whole grinding bed so that'it does not pass therethro-ugh too locally.

In order to obtain uniformity in a structurally simple manner, according to the invention the material to be ground together with separating air is supplied to a jacket surrounding the grinding container, from which jacket said material and said air pass through a plurality of inletopenings in the container wall int-o the container, so that the separating air is passed through the grinding bed as uniformly as possible.

Preferably according to the invention the inlet openings for separating air and material to be ground are located in the lower zone only of the container wall, i. 'e., at the deepest point of the container which vibrates over a small path only.

In the accompanying drawings forming a part of this specification, Fig. 1 shows an oscillatory mill according to the invention in elevation, in part in section. Fig. 2 is a section on the line II-II in Fig. 1.

In the drawings 1 is a vibrating supply gutter for the coarse material to be ground, said gutter being spring supported and actuated in aknown manner. A grinding container 2, filled with grinding balls '3 and located underneath said supply gutter 1, is mounted on a horizontal operating shaft 4 carrying unbalanced masses 5 and 6 by means of supports 7 and ballor roller bearings 8. The grinding container 2 s surrounded by a jacket 9, the outer wall 10 of which is integral with the container and is spring supported by means of springs 11 between foundation elements 12 and lateral extensions 13 of the jacket 9. The container 2 is provided with an upper wall 14 having downwardly sloping wall portions 15, 16 (Fig. 2) and a central pipe opening 17 connected to a vertical air discharge pipe 18. The lower zone or bottom wall portion of the container is provided with a plurality of inlet openings 19 for separating air and material to be ground, said openings being uniformly distributed over said lower zone. Said openings might be slots.

The air-discharge pipe 18 is connected to an airdischarge pipe section 20 by means of a hose or coupling sleeve 21 allowing for the movements imparted to the pipe 18 by the vibrating container 2. The pipe section 20 is connected to a separator 22 which may be a cyclone either with rotatable or without movable parts. From this separator grit is discharged through a conduit 23 entering at 24 into an inclined supply duct 25, which at its open upper end 26 receives the coarse material to be ground and at its lower bifurcated end 27, 28 discharges this material together with said grit onto the upper wall 14 of the container 2 from which it passes into the jacket 9 together with separating air.

The comminuted material and separating air pass from the separator 22 through a conduit 29 and the comminuted material is then separated from said air in a cyclone 30 and discharged at 31. The separating air, which is practically free from dust, passes through a conduit 32, a suction fan 33 and the discharge conduit 34 thereof to a zone 35 from which at 36 the remainder of the dust, if any, can be removed by means of a worm 37.

Since the vibrating container 2 is under sub-atmopheric pressure the separating air enters the jacket 9 together with the coarse material supplied. The stream of air coming from the inlet openings 19 will be subjected to an intensive spreading when flowing through the ball filling and owing to its impact with said ball filling a considerable separation will already be effected. The intensively spreading stream whose speed rapidly decreases will mainly leave the greater part of the grit in the grinding bed. Subsequently the dust laden air passes through the pipe 18 which is connected to the empty zone of the vibrating container 2.

A special advantage of the invention is that for this air separation use can even be made of oscillating mills which oscillate alternately in clockwise or in counterclockwise direction. Such a device is also shown in Figure 1. Reference numeral 38 designates the upper boundary line of the grinding bed, when the device is oscillating in the direction of the arrow of the circle 39, whereas on the other hand 40 designates the boundary line when the device is actuated by oscillations in the sense of the arrow 41.

When the vibrating container 2 is adapted to oscillate in both directions a heart shaped boundary 42 will form the upper closure of the container 2, so that when the direction of oscillation is about periodically changed even the finest material will. not be deposited on the walls. The heart shaped upper part of the vibrating mill only contains longitudinal slots for discharging the separating air from the greatly increased cross section.

This application is a continuation-in-part of my appli cation 298,785, filed July 14, 1952, and now abandoned.

Iclaim:

1. Oscillatory mill with air separation, comprising a rotary operating shaft carrying unbalanced masses, a grinding container mounted on said shaft, said container being provided in its upper wall with an outlet opening connected to an upstanding air discharge pipe and in another wall with a plurality of inlet openings for air and material to be ground, a jacket open at its upper edge and surrounding said container to which it is connected so as to oscillate therewith, and means for supplying material References Cited in the file of this patent UNITED STATES PATENTS 75,912 Hoffman Mar. 24, 1868 2,117,965 Kiesskalt May 17, 1938 2,171,115 Kiesskalt Aug. 29, 1939 2,192,549 Hadsel Mar. 5, 1940 FOREIGN PATENTS 485,969 Great Britain May 27, 1938 

